Posted on August 22nd, 2009 by Scraps.
Categories: Stuff, Sports.
David Appleman wrote a post at the excellent baseball blog Fangraphs about Mark Teixeira and defense. Fangraphs is one of the best blogs about quantifying defense, especially their creation Ultimate Zone Rating. Appleman is replying to the New York Times sportswriter Tyler Kepner, who wrote:
I say off the charts because I’m convinced there is no chart that accurately measures defense. The attempt is a noble one; defense is easily the most underrated ingredient in how games are won. But I don’t fully accept it.
People often cite Ultimate Zone Rating, a metric that tries to measure range and errors and how they affect runs allowed or prevented. But how can that statistic be valid when it says Teixeria has had a negative defensive impact?
Appleman says that in fact UZR has historically showed Teixeria to be excellent; it's just this year that Teixeria measures out at average. Appleman spends time pointing out that the previous first baseman for the Yankees, Jason Giambi, was awful, and maybe that skews Kepner's perception. That's true -- even Kepner admits the possibility -- but as always, defense discussions and metrics frustratingly (to me) leave something big out:
The offensive baseball stats, both those widely-accepted and those not, understand that sometimes baseball players slump, even for whole seasons. Yet defensive stats are called out for anything that "sounds wrong", and dismissed thereby. Maybe Mark Teixeria, most of time an excellent player, is having, this year, a mediocre year defensively. I assume that defensive stats are as much subject to variability as offensive stats. It's wrong to write off a metric just because one year it doesn't tell you what you expect.
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